diff mbox series

virtiofsd: Fix side-effect in assert()

Message ID 20210409100627.451573-1-groug@kaod.org (mailing list archive)
State New, archived
Headers show
Series virtiofsd: Fix side-effect in assert() | expand

Commit Message

Greg Kurz April 9, 2021, 10:06 a.m. UTC
It is bad practice to put an expression with a side-effect in
assert() because the side-effect won't happen if the code is
compiled with -DNDEBUG.

Use an intermediate variable. Consolidate this in an macro to
have proper line numbers when the assertion is hit.

virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
 Assertion `fchdir_res == 0' failed.
Aborted

  2796          /* fchdir should not fail here */
=>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
  2798          ret = getxattr(procname, name, value, size);
  2799          FCHDIR_NOFAIL(lo->root.fd);

Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
Cc: misono.tomohiro@jp.fujitsu.com
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

Comments

Philippe Mathieu-Daudé April 9, 2021, 10:23 a.m. UTC | #1
On 4/9/21 12:06 PM, Greg Kurz wrote:
> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
> 
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
> 
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>  Assertion `fchdir_res == 0' failed.
> Aborted
> 
>   2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>   2798          ret = getxattr(procname, name, value, size);
>   2799          FCHDIR_NOFAIL(lo->root.fd);
> 
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Vivek Goyal April 9, 2021, 1:30 p.m. UTC | #2
On Fri, Apr 09, 2021 at 12:06:27PM +0200, Greg Kurz wrote:
> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
> 
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
> 
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>  Assertion `fchdir_res == 0' failed.
> Aborted
> 
>   2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>   2798          ret = getxattr(procname, name, value, size);
>   2799          FCHDIR_NOFAIL(lo->root.fd);
> 
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>

Looks good to me.

Reviewed-by: Vivek Goyal <vgoyal@redhat.com>

Vivek

> ---
>  tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index 1553d2ef454f..6592f96f685e 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -2723,6 +2723,11 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name,
>      return -ENODATA;
>  }
>  
> +#define FCHDIR_NOFAIL(fd) do {                         \
> +        int fchdir_res = fchdir(fd);                   \
> +        assert(fchdir_res == 0);                       \
> +    } while (0)
> +
>  static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>                          size_t size)
>  {
> @@ -2789,9 +2794,9 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>          ret = fgetxattr(fd, name, value, size);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = getxattr(procname, name, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      if (ret == -1) {
> @@ -2864,9 +2869,9 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
>          ret = flistxattr(fd, value, size);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = listxattr(procname, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      if (ret == -1) {
> @@ -3000,9 +3005,9 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>          ret = fsetxattr(fd, name, value, size, flags);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = setxattr(procname, name, value, size, flags);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      saverr = ret == -1 ? errno : 0;
> @@ -3066,9 +3071,9 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name)
>          ret = fremovexattr(fd, name);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = removexattr(procname, name);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      saverr = ret == -1 ? errno : 0;
> -- 
> 2.26.3
> 
> _______________________________________________
> Virtio-fs mailing list
> Virtio-fs@redhat.com
> https://listman.redhat.com/mailman/listinfo/virtio-fs
Wainer dos Santos Moschetta April 9, 2021, 2:40 p.m. UTC | #3
On 4/9/21 7:06 AM, Greg Kurz wrote:
> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
>
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
>
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>   Assertion `fchdir_res == 0' failed.
> Aborted
>
>    2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>    2798          ret = getxattr(procname, name, value, size);
>    2799          FCHDIR_NOFAIL(lo->root.fd);
>
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>   tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>   1 file changed, 13 insertions(+), 8 deletions(-)


Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>


>
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index 1553d2ef454f..6592f96f685e 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -2723,6 +2723,11 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name,
>       return -ENODATA;
>   }
>   
> +#define FCHDIR_NOFAIL(fd) do {                         \
> +        int fchdir_res = fchdir(fd);                   \
> +        assert(fchdir_res == 0);                       \
> +    } while (0)
> +
>   static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>                           size_t size)
>   {
> @@ -2789,9 +2794,9 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>           ret = fgetxattr(fd, name, value, size);
>       } else {
>           /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>           ret = getxattr(procname, name, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>       }
>   
>       if (ret == -1) {
> @@ -2864,9 +2869,9 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
>           ret = flistxattr(fd, value, size);
>       } else {
>           /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>           ret = listxattr(procname, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>       }
>   
>       if (ret == -1) {
> @@ -3000,9 +3005,9 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>           ret = fsetxattr(fd, name, value, size, flags);
>       } else {
>           /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>           ret = setxattr(procname, name, value, size, flags);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>       }
>   
>       saverr = ret == -1 ? errno : 0;
> @@ -3066,9 +3071,9 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name)
>           ret = fremovexattr(fd, name);
>       } else {
>           /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>           ret = removexattr(procname, name);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>       }
>   
>       saverr = ret == -1 ? errno : 0;
Alex Bennée April 9, 2021, 2:56 p.m. UTC | #4
Greg Kurz <groug@kaod.org> writes:

> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
>
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
>
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>  Assertion `fchdir_res == 0' failed.
> Aborted
>
>   2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>   2798          ret = getxattr(procname, name, value, size);
>   2799          FCHDIR_NOFAIL(lo->root.fd);
>
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Stefan Weil April 9, 2021, 3:11 p.m. UTC | #5
Am 09.04.21 um 12:06 schrieb Greg Kurz:

> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
>
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
>
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>   Assertion `fchdir_res == 0' failed.
> Aborted
>
>    2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>    2798          ret = getxattr(procname, name, value, size);
>    2799          FCHDIR_NOFAIL(lo->root.fd);
>
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>   tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>   1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index 1553d2ef454f..6592f96f685e 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -2723,6 +2723,11 @@ static int xattr_map_server(const struct lo_data 
*lo, const char *server_name,
>       return -ENODATA;
>   }
>   
> +#define FCHDIR_NOFAIL(fd) do {                         \
> +        int fchdir_res = fchdir(fd);                   \
> +        assert(fchdir_res == 0);                       \
> +    } while (0)
> +
>   static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>   


I am afraid that this will raise a compiler warning (or error with 
-Werror) when NDEBUG is defined because the variable is unused in that 
case ([-Wunused-variable]).

I suggest to use different implementations of the macro depending on NDEBUG.

Stefan
Philippe Mathieu-Daudé April 9, 2021, 3:24 p.m. UTC | #6
Hi Stefan,

On 4/9/21 5:11 PM, Stefan Weil wrote:
> Am 09.04.21 um 12:06 schrieb Greg Kurz:
> 
>> It is bad practice to put an expression with a side-effect in
>> assert() because the side-effect won't happen if the code is
>> compiled with -DNDEBUG.
>>
>> Use an intermediate variable. Consolidate this in an macro to
>> have proper line numbers when the assertion is hit.
>>
>> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>>   Assertion `fchdir_res == 0' failed.
>> Aborted
>>
>>    2796          /* fchdir should not fail here */
>> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>>    2798          ret = getxattr(procname, name, value, size);
>>    2799          FCHDIR_NOFAIL(lo->root.fd);
>>
>> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
>> Cc: misono.tomohiro@jp.fujitsu.com
>> Signed-off-by: Greg Kurz <groug@kaod.org>
>> ---
>>   tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>>   1 file changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/virtiofsd/passthrough_ll.c
>> b/tools/virtiofsd/passthrough_ll.c
>> index 1553d2ef454f..6592f96f685e 100644
>> --- a/tools/virtiofsd/passthrough_ll.c
>> +++ b/tools/virtiofsd/passthrough_ll.c
>> @@ -2723,6 +2723,11 @@ static int xattr_map_server(const struct lo_data 
> *lo, const char *server_name,
>>       return -ENODATA;
>>   }
>>   +#define FCHDIR_NOFAIL(fd) do {                         \
>> +        int fchdir_res = fchdir(fd);                   \
>> +        assert(fchdir_res == 0);                       \
>> +    } while (0)
>> +
>>   static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char
>> *in_name,
>>   
> 
> 
> I am afraid that this will raise a compiler warning (or error with
> -Werror) when NDEBUG is defined because the variable is unused in that
> case ([-Wunused-variable]).
> 
> I suggest to use different implementations of the macro depending on
> NDEBUG.

QEMU doesn't build with NDEBUG, see commit 262a69f4282
("osdep.h: Prohibit disabling assert() in supported builds").

Regards,

Phil.
Dr. David Alan Gilbert (git) May 6, 2021, 3:46 p.m. UTC | #7
* Greg Kurz (groug@kaod.org) wrote:
> It is bad practice to put an expression with a side-effect in
> assert() because the side-effect won't happen if the code is
> compiled with -DNDEBUG.
> 
> Use an intermediate variable. Consolidate this in an macro to
> have proper line numbers when the assertion is hit.
> 
> virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
>  Assertion `fchdir_res == 0' failed.
> Aborted
> 
>   2796          /* fchdir should not fail here */
> =>2797          FCHDIR_NOFAIL(lo->proc_self_fd);
>   2798          ret = getxattr(procname, name, value, size);
>   2799          FCHDIR_NOFAIL(lo->root.fd);
> 
> Fixes: bdfd66788349 ("virtiofsd: Fix xattr operations")
> Cc: misono.tomohiro@jp.fujitsu.com
> Signed-off-by: Greg Kurz <groug@kaod.org>

Queued

> ---
>  tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> index 1553d2ef454f..6592f96f685e 100644
> --- a/tools/virtiofsd/passthrough_ll.c
> +++ b/tools/virtiofsd/passthrough_ll.c
> @@ -2723,6 +2723,11 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name,
>      return -ENODATA;
>  }
>  
> +#define FCHDIR_NOFAIL(fd) do {                         \
> +        int fchdir_res = fchdir(fd);                   \
> +        assert(fchdir_res == 0);                       \
> +    } while (0)
> +
>  static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>                          size_t size)
>  {
> @@ -2789,9 +2794,9 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>          ret = fgetxattr(fd, name, value, size);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = getxattr(procname, name, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      if (ret == -1) {
> @@ -2864,9 +2869,9 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
>          ret = flistxattr(fd, value, size);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = listxattr(procname, value, size);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      if (ret == -1) {
> @@ -3000,9 +3005,9 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
>          ret = fsetxattr(fd, name, value, size, flags);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = setxattr(procname, name, value, size, flags);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      saverr = ret == -1 ? errno : 0;
> @@ -3066,9 +3071,9 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name)
>          ret = fremovexattr(fd, name);
>      } else {
>          /* fchdir should not fail here */
> -        assert(fchdir(lo->proc_self_fd) == 0);
> +        FCHDIR_NOFAIL(lo->proc_self_fd);
>          ret = removexattr(procname, name);
> -        assert(fchdir(lo->root.fd) == 0);
> +        FCHDIR_NOFAIL(lo->root.fd);
>      }
>  
>      saverr = ret == -1 ? errno : 0;
> -- 
> 2.26.3
> 
>
diff mbox series

Patch

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 1553d2ef454f..6592f96f685e 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2723,6 +2723,11 @@  static int xattr_map_server(const struct lo_data *lo, const char *server_name,
     return -ENODATA;
 }
 
+#define FCHDIR_NOFAIL(fd) do {                         \
+        int fchdir_res = fchdir(fd);                   \
+        assert(fchdir_res == 0);                       \
+    } while (0)
+
 static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
                         size_t size)
 {
@@ -2789,9 +2794,9 @@  static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
         ret = fgetxattr(fd, name, value, size);
     } else {
         /* fchdir should not fail here */
-        assert(fchdir(lo->proc_self_fd) == 0);
+        FCHDIR_NOFAIL(lo->proc_self_fd);
         ret = getxattr(procname, name, value, size);
-        assert(fchdir(lo->root.fd) == 0);
+        FCHDIR_NOFAIL(lo->root.fd);
     }
 
     if (ret == -1) {
@@ -2864,9 +2869,9 @@  static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
         ret = flistxattr(fd, value, size);
     } else {
         /* fchdir should not fail here */
-        assert(fchdir(lo->proc_self_fd) == 0);
+        FCHDIR_NOFAIL(lo->proc_self_fd);
         ret = listxattr(procname, value, size);
-        assert(fchdir(lo->root.fd) == 0);
+        FCHDIR_NOFAIL(lo->root.fd);
     }
 
     if (ret == -1) {
@@ -3000,9 +3005,9 @@  static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
         ret = fsetxattr(fd, name, value, size, flags);
     } else {
         /* fchdir should not fail here */
-        assert(fchdir(lo->proc_self_fd) == 0);
+        FCHDIR_NOFAIL(lo->proc_self_fd);
         ret = setxattr(procname, name, value, size, flags);
-        assert(fchdir(lo->root.fd) == 0);
+        FCHDIR_NOFAIL(lo->root.fd);
     }
 
     saverr = ret == -1 ? errno : 0;
@@ -3066,9 +3071,9 @@  static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name)
         ret = fremovexattr(fd, name);
     } else {
         /* fchdir should not fail here */
-        assert(fchdir(lo->proc_self_fd) == 0);
+        FCHDIR_NOFAIL(lo->proc_self_fd);
         ret = removexattr(procname, name);
-        assert(fchdir(lo->root.fd) == 0);
+        FCHDIR_NOFAIL(lo->root.fd);
     }
 
     saverr = ret == -1 ? errno : 0;